Helicopters have been successful and are very widely used, but the most common configuration suffers from a number of challenges which, although managed successfully in conventional helicopters, nevertheless make them difficult to fly, inefficient, riskier than other types of aircraft, and cause them to require frequent and careful maintenance.
The conventional helicopter configuration comprises a single lift rotor and a tail rotor. The latter is required because the main rotor applies a torque to the aircraft which must be canceled, and the tail rotor is used to cancel the main rotor torque. The importance of this is evident when one sees what happens to the craft if the tail rotor is destroyed or damaged. The helicopter goes into what is usually a fatal spin.
Another complication of conventional rotorcraft arises because of what is necessary to produce forward flight, as distinct from stationary hovering. Assume the direction of rotation of the main rotor is clockwise from the top. When traveling forward at any significant speed, the rotor blades, when they are on the left side of the vehicle, travel toward the incoming air stream, creating increased lift. For balance, the pitch of the blade must be decreased when rotating on the left side in order to maintain constant lift. On the other side, the blades travel away from the incoming air stream, reducing lift. Therefore the pitch of the same blade must be increased when the blade travels on the right side (for a clockwise rotation) to keep lift constant.
To correct for these unwanted positive and negative lift forces, a mechanism that decreases the blade pitch when it is on the left side of the aircraft and increases it when the blade is on the rights side of the aircraft is employed. This mechanism constantly operates, changing the pitch every rotation of the blade. In addition, in order for the helicopter to fly in a forward direction, the same mechanism must increase the pitch of the blade when it is in the rear part of its rotation and/or decrease the pitch when it is in the forward portion to tilt the aircraft so that the main blade furnishes a forward thrust. For rearward flight, the opposite must occur. All of this involves a “swashplate”, as it is called, to perform the pitch adjustments every cycle of the rotor. As would be expected, this mechanism is fated for a great deal of wear and tear besides creating an environment for severe vibration.
According to other rotorcraft configurations, such as a two rotor aircraft, for example the Chinook, the torque problem is eliminated but the other challenges remain, such as the need for a swashplate and its concomitant drawbacks.
An object of the current invention is to provide a rotorcraft in which rotation of the rotors do not result in unwanted positive and negative lift and which has no need of a swashplate or similar mechanism to perform a plurality of pitch adjustments during each cycle of the rotor.
There are a number of rotorcraft “drone” configurations that have four blades, one on each corner of the aircraft fuselage. This configuration cancels the torque produced by a single rotor by arranging the rotors such that adjacent blades rotate in opposing directions, resulting in two blades rotating in one direction while the other two rotate in the other direction. However, these drones are relatively small, lightweight objects, and the blades are fairly short and non-intersecting. The result is that the devices use considerably more energy to stay aloft for a given weight than they would if the rotor blades were much longer, rotating at lower speeds, rendering them impracticable for vehicles that carry passengers and cargo.
Other four-rotor aircraft have been built or proposed, sometimes termed “quadrotor” aircraft, wherein the rotors are longer and intersect or overlap, as illustrated in FIG. 1, but require synchronization of all rotors to prevent the rotors from colliding.
A further object of the current invention is to provide for a quad-rotor aircraft having four intersecting rotors with adjacent rotors rotating in opposed directions that employs novel synchronization mechanisms to prevent rotor collision while promoting safety and efficiency of operation and flight.
Another object of current invention is to provide for a quad-rotor aircraft with intersecting rotors wherein the rotation of the rotors are synchronized by more than one method simultaneously.
Another object of current invention is to provide for a quad-rotor aircraft with intersecting rotors that is more efficient, safer, and easier to maintain than currently available quad-rotor aircraft.
Other objects and advantages of the current invention will be obvious to those skilled in the relevant art from the ensuing description and the drawings referenced therein.